An electric motor can comprise a housing defining an essentially air-tight chamber, a stator positioned within the chamber, a rotor for rotation within the stator, a shaft rotating with the rotor and coupled to drive to a component (e.g., a hydraulic pump). In an air-cooled electric motor, the non-drive end of the shaft can have a fan attached thereto and a cover can surround the housing. The fan can be positioned in a cavity between the housing and the cover, and a series of channels can be formed between the housing and the cover. The channels can receive ambient air at the fan-end of the housing and extend axially through the channels to the drive-end of the housing, whereby air can be pushed therethrough by the fan for cooling purposes.
In an aerospace application, the motor will be subjected to a range of ambient pressures depending upon the altitude of the aircraft. For example, the ambient pressure can drop by 60% to 70% at cruise altitudes of 30,000 ft. or higher, and the motor housing must be designed to withstand the mechanical stresses associated with such barometric pressure differentials. This can be accomplished by the motor housing being made of a high strength material (e.g., steel or high strength aluminum alloy) and/or its housing wall being of a sufficient thickness.